A typical semiconductor fabrication facility can cost billions of dollars. In view of the high capital costs associated with building and maintaining a semiconductor fabrication facility, it would be desirable to decrease the time needed to process semiconductor wafers into chips. By reducing the cycle time for chip production, more chips can be produced in less time, thus maximizing the use of equipment in a fabrication facility.
One time-consuming processing step in a chip manufacturing process is the evacuation and re-pressurization of load-locks, transfer chambers, and processing chambers. For example, FIG. 1 shows a deposition module 120 that can be used to deposit layers on semiconductor substrates. In operation, a loadlock chamber 124 in a front end staging area 122 is loaded with cassettes containing semiconductor substrates and is pumped down to near vacuum. The front staging area 122 can be connected to another processing module (not shown).
A transfer chamber 126 adjacent to the staging area 122 is pumped down to vacuum or near vacuum using one or more vacuum pumps (not shown) disposed on the deposition module 120. After vacuum pumping to a sufficiently low pressure, the vacuum doors 128 of the transfer chamber 126 open so that the transfer chamber 126 and the front end staging area 122 are in communication with each other. Movable arms on a substrate handler 127 in the transfer chamber 126 retrieve substrates from the loadlock chamber 124. The substrate handler 127 in the transfer chamber 126 then transfers the substrates into the processing regions 618, 620 of one of the processing chambers 130.
Once the semiconductor substrates are placed in the processing chambers 130, the arms of the substrate handler 127 are withdrawn. The slit valves 132 to the processing chamber 130 are then closed. Other processing chambers may be loaded with substrates in a similar manner. In each processing chamber 130, layers of material (e.g., capping layers) are respectively deposited on the substrates using, for example, a plasma enhanced chemical vapor deposition (PECVD) process. After processing is finished, the slit valves 132 are opened and the arms of the substrate handler 127 retrieve the substrates from the processing regions 618, 620. The substrates are then returned to the loadlock chamber 124. Then, the substrate handler 127 retrieves another pair of substrates from the loadlock chamber 124, and the processing continues in the same manner.
After all of the substrates in the loadlock chamber 124 are processed, the slit valves 132 to the processing chambers 130 are closed. The transfer chamber 126 is then vented to atmosphere pressure using an inert gas (e.g., argon) and the front vacuum doors 128 are opened. Another substrate handler (not shown) can then retrieve the processed substrates from the loadlock chamber 124.
A significant amount of time is needed to evacuate and re-pressurize the processing chambers, the transfer chamber, and the loadlock chambers in the substrate processing apparatus. It would be desirable to reduce the time associated with one or more of these steps to reduce the amount of time needed to process the substrate. Doing so would increase processing efficiency and would reduce the cycle time associated with manufacturing, for example, semiconductor chips.
Embodiments of the invention address this and other problems.